Why would you claim this? There are no limitations on web browsers.
All browsers on iOS must use the WebKit browser engine making them, in essence, safari clones with a different look and feel.
Some browsers do have their own extensions (Edge has AdBlock Plus built-in, but that's all; iCab has quite a few Javascript-based extensions) and of course you get things like using another vendor's bookmark and password sync. But that's about it.
Of course, there are (supposed-to-be-but-aren't) browser-agnostic WebExtensions — but again, only Safari implements them on iOS (starting with iOS 15), they must be bundled with an iOS app, and non-Safari browsers don't have access to those bundled extensions.
Perhaps those browsers will implement support for WebExtensions by some other mechanism but it certainly won't be the case that Firefox for iOS could run extensions intended for Firefox on desktop, nor would one expect extensions from the Chrome Web Store to work properly on Chrome for iOS.
Perhaps that's an upshot? Better support for browser-agnostic WebExtensions?
Even then, that's up to whether or not Apple permits that in the App Store.
There's no way to avoid the Apple. It's become the Berlin Wall of computing. No admittance, no escape, secret police, protection racket.
Companies with apps don't have customers. They're unnaturally fenced off, cajoled, and taxed. Apple laughably claims privacy.
Meanwhile device owners can't repair their phones or expect not to be spied on. When they aren't paying $500 for RAM, they're letting Apple define what activities are permissible.
The damn thing doesn't even have a web browser that isn't safari. The Apple is so afraid of runtimes threatening the app store distribution model.